This wallpaper process is perplexing! I've tried just now 600w x 1024h for a single panel on my Nook Color and when I go to set it as my wallpaper, it looks fine until that cropping box comes up {which you cannot avoid}. Then when I touch save, it always enlarges my photo and hence ruining the whole background perspective.

I've spent all day on this off and on. My picture is a .png. 600w x 1024h , 192 dpi.